CBD Extraction Process Explained - Extraction, Purification, Final Processing

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"This article mainly introduces the different methods and general processes of CBD extraction, such as Extraction, Purification, Final Processing. "
CBD Extraction Process Explained-Extraction Purification Final-Processing

With the increasing popularity of CBD products worldwide, China's related industries have also begun to transform to adopt this new craze gradually. Although the CBD infused products are currently illegal in China, some companies of cannabis extraction supply chain have already been integrating this market.

These companies aim to develop better quality CBD extraction technologies. At present, only 4 companies (Hankang Bio, Hansu Bio, Hempson Bio, and BiouNIO Bio) that have technology capability and licenses for processing cannabis flowers and leaves in China and the related technologies. The patents related to the CBD extraction of these companies have also been public.

It is important to know that the extraction of CBD in China is not something that any biotech company can do. Today Vapebiz will provide an in-depth introduction to the process of extracting CBD in China for the published information of these companies.

The Value of CBD

Before the CBD extraction technology, let have a quick look at the CBD.

The full name of the CBD is Cannabidiol, which is one of hundreds of cannabinoids. It is the main component of industrial cannabis and is extracted from female cannabis plants.

CBD is none-psychoactive, and it has pharmacological effects such as anti-caries, anti-anxiety, and anti-inflammatory. Also, CBD can eliminate the hallucinogenic effects of tetrahydrocannabinol (THC) on the human body. Known as anti-poisoning compounds. These two attributes will determine that CBD is the most valuable product of industrial cannabis.

Molecular Formula of Cannabidiol (CBD)
Molecular Formula of Cannabidiol (CBD)

The CBD was originally an organic compound isolated from cannabis indica by Adams and Todd in 1940. In 1963 Mechoulam and Shvo measured their chemical structures. The chemical formula of CBD is C₂₁H₃₀O₂ with a molecular weight of 314.46 Daltons.

More about CBD and THC, just read the chapter1 of this article: [Exclusive Expert Interview] China: Cannabis Research And Policy Prospects – Marcus, Vapebiz

Structurally, CBD is optically active and has cis-trans isomers. The natural CBDs are all left-handed trans-structures, ie (-)-trans-CBD. Under normal temperature, the CBD is white or pale yellow fat or crystal, melting point 66-67 ℃, boiling point 463.9 ℃ (760 mmHg), density 1.025 g/cm³, almost insoluble in water, soluble in organic solvents.

Since the chemical formula and molecular weight of CBD are completely consistent with THC, the physical and chemical properties of the two are very close. Therefore, it is difficult to extract CBD from industrial cannabis, which constitutes the technical barrier of related enterprises.

Since the chemical formula and molecular weight of CBD are completely consistent with THC, the physical and chemical properties of the two are very close. Therefore, it is difficult to extract CBD from industrial cannabis, which constitutes the technical barrier of related enterprises.

CBD Extraction

What's CBD Extraction Technology

The main methods used for the efficient extraction of CBD components (usually organic compounds) in cannabis plants include steam distillation, pressing and extraction.

The distillation method is suitable for substances with strong volatility, and the pressing method is suitable for extracting the eschar materials which are liquid at normal temperature. Since the CBD has a boiling point of about 400 °C at normal temperature and pressure and is insoluble in water, the extraction method is the most suitable extraction method.

After understanding the current CBD extraction method, we can summarize the CBD extraction process into the following process, which is divided into four parts:

  • Pre-processing: Extraction Raw Material > Pulverization Drying > Powder
  • Extraction: Powder > Extraction > Extract
  • Purification: Extract > Concentrate > Ointment > Purification by Dissolution Chromatography > Eluent
  • Final Processing: Eluent > Evaporation / Drying / Saturating > CBD Crystal or CBD Oil

It can be seen from the above that the extraction of the CBD is carried out by a pre-processing step such as pulverization and drying, an extraction step, a post-extraction concentration and a chromatographic purification step, and a final processing step on the purified sample. Among these steps, extraction and purification are key factors in the extraction of CBD.

Raw Material Selection

The first step in the CBD extraction process is the selection of raw materials. The level of CBD in the raw materials has a direct impact on the yield and purity of the final extraction. The higher the content of CBD in the raw materials, the higher the return under the same process conditions. Similar to THC, the content of CBD in various parts of cannabis is usually reduced in the order of bracts, flowers, leaves, stalks and thick stems, and is highest in flowers and leaves of female flowers. Therefore, the processing of the CBD is usually carried out using mosaics.

In the treatment of raw materials, drying and comminution steps are usually included. The water in the raw material is reduced to 8% or less by heat drying or natural air-drying. The number of meshes is usually between 50 and 200, the purpose of increasing the extraction efficiency is to increase the contact area with the extraction reagent during the extraction process. There are also companies that use cellulase, pectinase or complex enzymes after drying and pulverizing to destroy the cell wall of cannabis to further improve extraction efficiency. However, the addition of enzymes will also increase production costs. From the perspective of industrial production, the addition of enzymes may require careful consideration.

Vapebiz has to mention another unfortunate thing, that is, China's existing cannabis policy is somehow blocking CBD R&D. Because the extraction of CBD is directly related to different cannabis strains containing different content and purity of CBD.

The problem is that China’s cannabis strains are not suitable for CBD extraction, and the yield is obviously insufficient. Coupled with the policy to limit the amount of overseas purchase of seeds up to 30kg per year, Chinese cannabis companies cannot effectively extract CBD, and also China's cannabis strains are much less competitive than foreign counterparts. This is why Europe and America do not give priority to purchasing industrial cannabis plants and seeds from China.

However, in the Chinese policy environment, the CBD content problem has to be comprehensively considered, because the industrial cannabis THC value must be less than 0.3% as per existing law but the CBD is the isomer of THC, the content of the two substances is positively correlated in the same cannabis strain.

[Exclusive Expert Interview] China: Cannabis Research And Policy Prospects - Marcus, Vapebiz
CBD Concentration and Chromatographic Purification

How to Extract CBD

Commonly used extraction methods in CBD include organic solvent extraction and supercritical carbon dioxide extraction. There are also companies that use subcritical water extraction. Chinese industrial cannabis companies use organic solvent extraction methods.

The main advantages of the organic solvent extraction method are that the operation is simple, the requirements on the equipment and the energy consumption are low, and the disadvantage is that the organic solvent is liable to remain, the solvent dissolving ability is fixed, and improper treatment may cause environmental pollution.

The main advantage of the supercritical carbon dioxide extraction method is that the separation range is wide, and the adjustment of the dissolution capacity can be achieved by changing the temperature and pressure, but the equipment requirements are high, the energy consumption is large, and the instrument cleaning is difficult.

The subcritical water extraction method uses subcritical water for extraction, which reduces energy consumption to a certain extent compared with supercritical carbon dioxide extraction, and also reduces environmental pollution.

At present, organic solvent extraction and supercritical carbon dioxide extraction are widely used. Subcritical water extraction is a new technology, and China has not been used in the industrial production of CBD. The following is a comparison of Solvent Extraction and Supercritical Carbon Dioxide (ScCO₂) Supercritical Extraction:

  • Solvent Extraction
CBD Solvent Extraction
CBD Solvent Extraction, Credit: powerblanket.com
  1. Unable to avoid solvent residue
  2. Heavy metal
  3. Solvent melting capacity is fixed
  4. Need extra steps to get rid of dissolution
  5. May be extracted into inorganic salts
  6. Low cost, easy to maintain equipment
  • Supercritical Carbon Dioxide (ScCO) Extraction
CBD Supercritical Carbon Dioxide (ScCO₂) Extraction
CBD ScCO₂ Extraction, Credit: powerblanket.com
  1. Completely solvent-free residue
  2. No heavy metal
  3. Solubility changes with temperature and pressure
  4. High yield after separation
  5. Poor decomposition ability to water solubility, no residual inorganic salts
  6. High equipment cost, high-loss, and difficult to maintain

More about Supercritical Carbon Dioxide (ScCO) Extraction, just read: A Guide To CO2 Extraction Of Cannabis Oil - Hempgazette

On the other hand, the organic solvent extraction method can also be divided into soaking extraction, reflux extraction, and ultrasonic extraction.

  • Soaking Extraction is to directly extract and mix the organic solvent and the raw material, and the consumption is also long.
  • The Reflux Extraction is carried out by heating and distilling the leachate, distilling it and then condensing it, and then refluxing it to the leacher for extraction. Although this method improves the extraction efficiency, it may cause damage to the CBD due to continuous heating.
  • Ultrasonic Extraction is a method that uses ultrasonic mechanical effects, cavitation effects, and thermal effects to improve extraction efficiency. It can be carried out at lower temperatures, with faster extraction, higher efficiency, and less solvent usage, which is superior to the former two.
How to Extract CBD

CBD Concentration and Chromatographic Purification

The extract obtained by the extraction usually needs to be concentrated by heating, evaporated, and the extraction solvent is removed, and an extract composed of a component such as CBD is left.

Evaporation and concentration can not only remove some volatile impurities, but also replace the solvent with the mobile phase required for chromatography, which is convenient for chromatographic purification. The steps of replacing the solvent are more flexible, and the changes caused by different technologies are also large. Some techniques use water sedimentation to concentrate, and some techniques use organic solvents to dissolve and concentrate multiple times.

The extract is dissolved in a solvent using a chromatographic mobile phase and then purified by a column. Column purification is performed based on differences in properties such as molecular weight and polarity.

Commonly used column packings include silica gel, macroporous adsorption resin, polyamide adsorption resin, and the like. Each can be subdivided according to chemical composition or cross-linking. Chromatographic elution solvents often use polar or non-polar organic solvents.

Different chromatographic columns, as well as different solvents, can remove different impurities, and the recovery rate is different. Some technologies will be combined with various chromatographic columns for purification to improve the extraction purity of CBD. However, in the chromatographic process, the purity is usually not compatible with the recovery rate. The selection of the column, the choice of the chromatographic solvent and the choice of the chromatographic purification method require comprehensive consideration.

  • Silica gel column: Purification based on molecular polarity;
  • Macroporous adsorption resin column: Purification is based on molecular polarity and molecular weight;
  • Polyamide adsorption resin column: Purification based on molecular polarity;
  • Neutral alumina column: Purification is based on Lewis acid/base, molecular polarity, molecular charge.
CBD Process

Post-purification Processing

The post-purification processing is the final step of CBD extraction. The chromatographically purified CBD solution also needs to be concentrated to remove the solvent to obtain a higher purity CBD oil or ester. The CBD crystal or CBD oil is then prepared by evaporation, drying or supersaturation.

At present, the main goal of CBD extraction technology is to avoid the use of toxic organic solvents to improve product safety and prevent environmental pollution while improving the extraction rate and purity of CBD and removing THC residues as much as possible. reduce manufacturing cost.

Of course, before this premise is reached, Chinese industrial cannabis companies still have a long way to go, on the one hand, limited to policy, on the other hand, it is impeding to extract patents.

It is understood that Hansu Biotech's patented technology is in the process of actual examination in China and has applied for PCT patents. According to the announcement of Meilleure Health International, Hansu Bio's patent has recently been authorized in the United States, but the authorized version has not been announced yet.

This is the first international patent of medical CBD extraction obtained by Chinese cannabis company, which indicates that Chinese manufacturers have gained international recognition in the most demanding medicinal (high-purity) extraction of technology and industry, which is the first time for Chinese manufacturers to achieve high global scale. After the industrial extraction of purity CBD, another landmark development in the industrial cannabis field in China.

If in the future, China's cannabis policies can assist and strengthen technological advancement in the industrial cannabis field, perhaps related companies can achieve better results, and the government can also pass the scientific and technological practices of new industries to achieve profit.

Further Reading:

In the next issue, Vapebiz will report on 4 Chinese industrial cannabis companies for more about the development of the Chinese cannabis industry.

Editor: Marcus

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